Goldsmith is the middle child of the late financier Sir James Goldsmith, who left him between £200 and £300 million from his £1.2 billion fortune (1997).

From 1998 to 2007, he was editor of The Ecologist magazine. During this time, he became a London campaigner and commentator on environmental issues. Goldsmith became a Conservative Party parliamentary candidate in 2005. That same year, he was appointed deputy chairman of the Conservative Quality of Life Policy Group, co-authoring its report published in 2007. He was placed on the party's "A-List" of prospective parliamentary candidates by David Cameron, the Leader of the Opposition, in 2006.